Processes for preparation of 2-alkyl-2-adamantyl esters

ABSTRACT

A magnesium halide salt of a 2-alkyl-2-adamantanol is reacted with a carboxylic acid halide such as acrylic chloride or the like in the presence of a tertiary amine to produce a 2-alkyl-2-adamantyl ester (the first invention). 
     A 2-alkyl-2-adamantanol is reacted with a carboxylic acid such as acrylic acid or the like in the presence of an acid catalyst such as concentrated sulfuric acid or the like and a drying agent composed of an acidic or neutral inorganic compound (e.g. magnesium sulfate) which is a solid at ordinary temperature in a dried state or of a water-absorbing high-molecular compound, to produce a 2-alkyl-2-admantyl ester (the second invention). 
     The above ester is important as a raw material for a resist for semiconductor production.

TECHNICAL FIELD

The present invention relates to a process for producing a2-alkyl-2-adamntyl ester which is useful as, for example, a raw materialfor semiconductor resist.

BACKGROUND ART

It is reported in, for example, JP-A-5-265212 that resists produced byusing a 2-alkyl-2-adamantyl ester as a raw material shows highresistance to dry etching in a process for production of semiconductor.Therefore, attention is being paid to a future prospect of2-alkyl-2-adamantyl ester as a raw material for semiconductor resist.

For production of 2-alkyl-2-adamantyl ester, there are known, forexample, a process which comprises subjecting 2-adamantanone toalkylation using an alkylation reagent composed of an organometalliccompound and then subjecting the resulting metal salt of2-alkyl-2-adamantanol to acylation using a carboxylic acid halidecompound. Specifically, it is described in JP-A-10-182552 that2-methyl-2-adamantyl methacrylate is obtained at a yield of 85.0% byusing 2-adamantanone, methyl magnesium bromide and methacrylic chloride.

In such a production process, conditions are known in which analkylation reaction of 2-admantanone using methyl magnesium bromideproceeds stoichiometrically. Therefore, the yield of the latter step,i.e. the acylation reaction of magnesium halide salt of adamantanol hasan influence on the yield and purity of intended product, i.e.2-alkyl-2-adamantyl ester.

The present inventors traced the acylation reaction described in theabove literature; however, the reaction was not complete even when thereaction was made at room temperature for 15 hours, the conversion was86%, and the purity of the intended product obtained was 77%.

When the 2-alkyl-2-adamantyl ester is used as a raw material forsemiconductor resist, the ester is required to have a high purity. Inthe conventional production process therefor, however, the conversion inacylation is low as mentioned above and complicated purification isnecessary, making it impossible to produce a 2-alkyl-2-adamantyl esterof high purity efficiently.

Further, the carboxylic acid halide compound used in the productionprocess is ordinarily produced from a carboxylic acid compound andtherefore is more expensive than the carboxylic acid compound.Furthermore, the carboxylic acid halide compound is highly reactive perse and therefore may require care in handling.

Incidentally, as a general process for production of an ester compound,there is a process which comprises reacting an alcohol compound with acarboxylic acid compound in the presence of an acid catalyst. In thisprocess, the reaction is conducted with removing the water as by-productby azeotropic dehydration (for example, Azeotropic Dehydration, OrganicSynthesis 1973, Vol. V, p. 762).

The process is conducted by a simple operation and therefore isparticularly useful as an industrial process for production of estercompound when the alcohol compound and carboxylic acid compound used areinexpensive.

In this process, however, dehydration reaction of alcohol takes placepreferentially as shown in Comparative Example 7 described later, when atertiary alcohol such as 2-alkyl-2-adamantanol is used as a rawmaterial. As a result, the process has a problem in that the yield ofalkyladamantyl ester is strikingly low.

DISCLOSURE OF THE INVENTION

In order to solve the above problems, the present inventors made a studyon a method by which the reaction of a magnesium halide salt of a2-alkyl-2-adamantanol with a carboxylic acid halide compound can beallowed to proceed efficiently. As a result, it was found out that thereaction of a magnesium halide salt of a 2-alkyl-2-adamantanol with acarboxylic acid halide compound proceeds quantitatively in a short timewhen the reaction is conducted in the presence of a tertiary aminecompound. The finding has led to the completion of the first invention.Hence, the first invention aims at providing a process for producing a2-aklyl-2-adamantyl alkyl-2-adamantyl ester of high purity efficiently.

The present inventors made a study also on utilization, in production ofa 2-alkyl-2-adamantyl ester, of the above-mentioned process forproduction of an ester compound using azeotropic dehydration. As aresult, it was found out that even when a reaction is conducted in thepresence of an acid catalyst, no dehydration of 2-alkyl-2-adamantanoltakes place when a particular drying agent is allowed to coexist andthat a 2-alkyl-2-adamantyl ester of high purity can be producedefficiently. This finding has led to the completion of the secondinvention.

Hence, the second invention aims at providing a efficient process forproducing a 2-alkyl-2-adamantyl ester of high purity using a2-alkyl-2-adamantanol as a starting material without using an expensivecompound such as carboxylic acid halide compound.

BEST MODE FOR CARRYING OUT THE INVENTION The First Invention

The first invention lies in a process for producing a2-alkyl-2-adamantyl ester, which comprises reacting a magnesium halidesalt of a 2-alkyl-2-adamantanol, represented by the following generalformula (1):

(wherein R¹ is an alkyl group of 1 to 6 carbon atoms, and X is a halogenatom) with a carboxylic acid halide compound in the presence of atertiary amine compound.

The present invention is not restricted by a theory. However, in thepresent invention, it is presumed that the tertiary amine compoundcoexisting in the reaction system activates the carboxylic acid halidecompound, a higher conversion is obtained thereby, and the2-alkyl-2-adamantyl ester obtained finally has a higher purity.Moreover, it is surprising that in the activation of the carboxylic acidhalide compound, the tertiary amine compound acts like a catalyst. Thatis, the carboxylic acid halide compound is activated sufficiently evenwhen the tertiary amine compound is used in an amount of less than 1mole (less than the stoichiometric amount) relative to 1 mole of thecarboxylic acid halide compound. For example, when in a reaction ofesterifying a magnesium halide salt of a 2-alkyl-2-adamantanol, of thegeneral formula (1) wherein R¹ is an alkyl group of 1 to 3 carbon atoms,a tertiary amine compound of 0.01 to 0.5 mole per 1 mole of a carboxylicacid halide compound is allowed to coexist, a 2-alkyl-2-adamantyl estercan be obtained at a conversion of about 95% in a short time.

When in the reaction, the carboxylic acid halide compound is used inexcess relative to the magnesium halide salt of a 2-alkyl-2-adamantanol,the resulting 2-alkyl-2-adamantyl ester may be decomposed by, forexample, the excess carboxylic acid halide or an acid which is a thermaldecomposition product thereof. In the production process of the presentinvention, however, such decomposition is thought to be prevented bycapturing of the acid or the like by the tertiary amine compound. Thisdecomposition is effectively prevented even when the molar ratio of thecarboxylic acid halide to the magnesium halide salt was changed in awide range.

In the production process of the present invention, a magnesium halidesalt of a 2-alkyl-2-adamantanol, represented by the general formula (1)is mixed and reacted with a carboxylic acid halide compound in thepresence of a tertiary amine compound to give rise to acylation toproduce a 2-alkyl-2-adamantyl ester of corresponding structure.

In the above general formula (1), R¹ is an alkyl group of 1 to 6 carbonatoms, and X is a halogen atom.

R¹ is not critical as long as it is an alkyl group of 1 to 6 carbonatoms. R¹ is preferably an alkyl group of 1 to 3 carbon atoms, such asmethyl group, ethyl group, propyl group, isopropyl group or the like inview of high utility as a raw material for a resist for semiconductorproduction.

As the halogen atom shown by X, there can be mentioned a fluorine atom,a chlorine atom, a bromine atom and an iodine atom. X is preferably achlorine atom or a bromine atom in view of the good availability of rawmaterial and most preferably a bromine atom in view of the highreactivity.

The magnesium halide salt of a 2-alkyl-2-adamantanol, represented by thegeneral formula (1), which can be preferably used in the presentinvention, can be exemplified by magnesium chloride salt of2-methyl-2adamantanol, magnesium bromide salt of 2-methyl-2-adamantanol,magnesium chloride salt of 2-ethyl-2-adamantanol, and magnesium bromidesalt of 2-ethyl-2-adamantanol. Of these, preferred is a magnesium halidesalt of a 2-alkyl-2-adamantanol, of the general formula (1) wherein R¹is an alkyl group of 1 to 3 carbon atoms, from the high reactivity, andparticularly preferred is magnesium bromide salt of2-methyl-2-adamantanol.

The compound represented by the general formula (1) can be producedeasily from 2-adamantanone and a Grignard reagent. The reaction productcan be used as it is. Or, it is as necessary purified by filtration,washing or the like and is used.

The carboxylic acid halide compound is not critical as long as it is ahalide compound of a carboxyl group-containing organic acid. As specificexamples of the carboxylic acid halide compound used in the presentinvention, there can be mentioned saturated carboxylic acid halidecompounds such as acetic fluoride, acetic chloride, acetic bromide,acetic iodide, propionic chloride, propionic bromide, propionic iodideand the like; unsaturated carboxylic acid halide compounds such asacrylic fluoride, acrylic chloride, acrylic bromide, acrylic iodide,methacrylic fluoride, methacrylic chloride, methacrylic bromide,methacrylic iodide and the like; and aromatic carboxylic acid halidecompounds such as benzoyl fluoride, benzoyl chloride, benzoyl bromide,benzoyl iodide, toluyl fluoride, toluyl chloride, toluyl bromide, toluyliodide, naphthoic fluoride, naphthoic chloride, naphthoic bromide andthe like.

Of these, preferred are carboxylic acid chlorides of 2 to 7 carbon atomsfor the high reactivity, and particularly preferred are acrylic chlorideand methacrylic chloride for the high utility as a raw material forsemiconductor resist.

As such carboxylic acid halide compounds, there can be used those whichare available as a reagent or as an industrial material, as they are, orthose obtained by subjecting such a reagent or industrial material asnecessary to purification such as recrystallization, distillation or thelike. Carboxylic acid halide compounds of low availability can besynthesized as follows. That is, a carboxylic acid fluoride, acarboxylic acid chloride, a carboxylic acid bromide and a carboxylicacid iodide can be easily synthesized respectively by reacting cyanuricfluoride, thionyl chloride, dibromotriphenylphosphorane and sodiumiodide with a corresponding carboxylic acid or carboxylic acid chloride.

The amount of the carboxylic acid halide compound used is not criticalbut is preferably 0.8 to 2.0 moles per 1 mole of the used magnesiumhalide salt of a 2-alkyl-2-adamantanol, more preferably 1 to 1.5 moles.When the amount is less than 0.8 mole, unreacted magnesium halide saltof a 2-alkyl-2-adamantanol remains in the reaction product, reducing thepurity of the reaction product. When the amount is more than 2.0 moles,an operation such as alkali treatment or the like is required forremoval of unreacted carboxylic acid halide compound in the reactionproduct, making the operation complicated.

In reacting the magnesium halide salt of a 2-alkyl-2-adamantanol withthe carboxylic acid halide compound, a tertiary amine compound isallowed to coexist. When the reaction is conducted in the absence of atertiary amine compound, the conversion is low and no intended object isattainable.

The tertiary amine compound used in the present invention can beexemplified by aliphatic tertiary amine compounds such astrimethylamine, triethylamine, tripropylamine, tributylamine,diisopropylmethylamine, diisopropylethylamine and the like; cyclictertiary amine compounds such as N-methylpyrrolidine,N-methylpiperidine, N-ethylpiperidine, N-methylmorpholine,N-ethylmorpholine and the like; cyclic unsaturated hydrocarbon tertiaryamine compounds such as pyridine, N,N-dimethylaminopyridine and thelike; and aliphatic tertiary diamine compounds such asN,N,N′,N′-tetramethylethylenediamine,N,N,N′,N′-tetraethylethylenediamine and the like. Of these, particularlypreferred are triethylamine and N-methylmorpholine for the industrialavailability and low cost. Incidentally, these tertiary amine compoundsare each available as a reagent and an industrial material.

The amount of the tertiary amine compound used is not critical but asufficient effect is obtained in an amount of 0.01 to 1.0 mole per 1mole of the carboxylic acid halide compound. The amount is preferably0.01 to 0.5 mole, particularly preferably 0.1 to 0.3 mole per 1 mole ofthe carboxylic acid halide compound in order to avoid excessive use,increase the rate of reaction and prevent the side reaction.

The reaction of the magnesium halide salt of a 2-alkyl-2-adamantanolwith the carboxylic acid halide compound in the presence of the tertiaryamine compound is not critical and can be conducted by mixing these rawmaterials for reaction appropriately. The reaction is preferablyconducted in a solvent in view of, for example, the operability and theeasiness of control of reaction conditions such as reaction temperatureand the like. Particularly preferably, the reaction is conducted bydissolving or suspending a magnesium halide salt of a2-alkyl-2-adamantanol and a tertiary amine compound in a solvent, addingthereto a carboxylic acid halide compound, and stirring the mixture.

The solvent used is not critical as long as it is stable to themagnesium halide salt of a 2-alkyl-2-adamantanol, the carboxylic acidhalide compound and the tertiary amine compound. The solvent ispreferably a hydrocarbon such as benzene, toluene or the like, or anether such as diethyl ether, diisopropyl ether, tetrahydrofuran,1,4-dioxane or the like, in view of the solubility of the abovecompounds, the rate of reaction, etc.

These organic solvents can be used singly or in admixture of two or morekinds. The amount of the organic solvent used is not critical but ispreferably 5 liters or less, particularly preferably 0.2 to 3 liters permole of the magnesium halide salt. of a 2-alkyl-2-adamantanol in view ofreactor yield, solubility and rate of reaction.

The reaction conditions used in the production process of the presentinvention are controlled depending upon, for example, the kinds, amountsand concentrations of the used raw materials for reaction, while theproceeding of reaction is confirmed by, for example, gas chromatography.Since the reaction is conducted at a high rate with the side reactionbeing suppressed, it is generally preferred that the reactiontemperature is 0 to 5° C. and the reaction time is 0.5 to 24 hours.Since this reaction is exothermic, it is preferred to conduct stirringduring the reaction in order to make uniform the liquid temperature ofreaction system.

By thus conducting the reaction, it is possible to obtain a2-alkyl-2-adamantyl ester having a molecular structure corresponding tothe molecular structures of the materials used. For example, whenmagnesium bromide salt of 2-methyl-2adamantanol is used as the magnesiumhalide salt of a 2-alkyl-2-adamantanol and methacrylic chloride is usedas the carboxylic acid halide compound, 2-methyl-2-adamantylmethacrylate is formed.

The isolation of a 2-alkyl-2-adamantyl ester from the reaction mixtureis conducted by an ordinary method. For example, first, the reactionmixture is washed with an aqueous acid solution to remove a magnesiumhalide from the reaction mixture; then, further washing with an aqueousalkali solution, water, etc. is conducted; the resulting organic layeris subjected to vacuum evaporation to remove the solvent containedtherein; thereby, a 2-alkyl-2-adamantyl ester is isolated.

According to the present production process, a 2-alkyl-2-adamantyl esteris formed nearly quantitatively; therefore, even when isolation isconducted by such a simple method, the resulting product has a highpurity. Therefore, the reaction mixture can be used per se withoutpurification, depending upon the application thereof. When a product ofhigher purity is needed, the resulting 2-alkyl-2-adamantyl ester ispurified by column chromatography, distillation, recrystallization orthe like, depending upon the properties of the ester.

According to the first invention of the present invention, a2-alkyl-2-adamantyl ester of high purity can be obtained from amagnesium halide salt of a 2-alkyl-2-adamantanol and a carboxylic acidhalide compound, in short time at a high yield in a simple operation.

The Second Invention

The second invention lies in a process for producing a2-alkyl-2-adamantyl ester, which comprises reacting a2-alkyl-2-admantanol with a carboxylic acid compound in the presence ofan acid catalyst and a drying agent composed of an acidic or neutralinorganic compound which is a solid at ordinary temperature in a driedstate or water-absorbing high-molecular compound.

According to the production process of the present invention, a2-alkyl-2-adamantyl ester can be obtained at a higher yield than when anordinary process using azeotropic dehydration is used. The drying agentused in the reaction of the present process can be separated from thereaction mixture after the reaction, by a simple operation such asfiltration or the like. The drying agent separated from the reactionmixture can generally be reutilized by regeneration. Moreover, since nocarboxylic halide compound is used as a reactant, the reaction can beconducted simply as mentioned previously with no necessity of worryingabout the cost and chemical instability of the compound.

When there is used, as the acid catalyst, a cationic ion exchange resinhaving sulfonic acid group as the ion exchange group (this resin ishereinafter referred to simply as cationic ion exchange resin), thecationic ion exchange resin can be separated from the reaction mixtureafter the reaction, together with the drying agent, by a simpleoperation such as filtration or the like; therefore, a2-alkyl-2-adamantyl ester of high purity can be obtained by a simplepost-treatment.

The 2-alkyl-2-adamantanol which is a starting material of the presentproduction process, has a structure in which an alkyl group and ahydroxyl group are bonded to the 2-position carbon atom of adamantanemolecule. The kind of the alkyl group of the 2-alkyl-2-adamantanol isnot critical and any known compound can be used.

A 2-alkyl-2-adamantanol having a straight or branched chain alkyl groupof 1 to 4 carbon atoms is important as a starting material of thepresent invention in view of the high utility as a raw material forsemiconductor resist.

As specific examples of the 2-alkyl-2-adamantanol, there can bementioned 2-methyl-2-adamantanol, 2-ethyl-2-adamantanol,2-propyl-2-adamantanol, 2-isopropyl-2-adamantanol and2-butyl-2-adamantanol.

Of these, 2-methyl-2-adamantanol or 2-ethyl-2-adamantanol isparticularly important for the high utility for resist production.2-Methyl-2-adamantanol is most preferred as a starting material in viewof the high reactivity.

As the 2-alkyl-2-adamantanol, those marketed commercially or thoseproduced using 2-adamantanone and an organometallic reagent can be usedas they are or after being purified as necessary by a method such asrecrystallization, sublimation or the like.

As to the carboxylic acid compound used as another raw material, thereis no particular restriction as long as it an organic compound havingcarboxyl group. As specific examples of the carboxylic acid compoundused in the present invention, there can be mentioned saturatedmonocarboxylic acid compounds such as formic acid, acetic acid,propionic acid and the like; saturated dicarboxylic acid compounds suchas oxalic acid, malonic acid, succinic acid and the like; unsaturatedcarboxylic acid compounds such as acrylic acid, methacrylic acid,propiolic acid, crotonic acid, maleic acid and the like; and carbon ringor heterocyclic ring carboxylic acid compounds such as benzoic acid,1-naphthoic acid, phthalic acid, nicotinic acid, 2-furancarboxylic acidand the like.

Of these, carboxylic acid compounds of 2 to 7 carbon atoms are preferredfor the high reactivity. Acrylic acid or methacrylic acid isparticularly preferred for the high utility as a raw material forsemiconductor resist. As to these carboxylic acid compounds as well,those marketed commercially can be used as they are or after beingpurified as necessary by a method such as recrystallization,distillation or the like.

The carboxylic acid compound reacts with the 2-alkyl-2-adamantanolnearly stoichiometrically and therefore is used in an amount of about 1mole per 1 mole of the 2-alkyl-2-adamantanol. However, it is preferredthat either of them is used in an excess for a higher reaction rate.Since the carboxylic acid compound is less expensive than the2-alkyl-2-adamantanol, the carboxylic acid compound is ordinarily usedin an amount of preferably 1 to 50 moles, more preferably 2 to 20 molesper 1 mole of the 2-alkyl-2-adamantanol.

The acid catalyst used in the present invention is not critical as longas it is an acid having an catalytic activity for enhancing the rate ofesterification reaction between the 2-alkyl-2-adamantanol and thecarboxylic acid compound, and any of such acids can be used.Specifically there can be used, as the acid catalyst, organic acids andinorganic acids which are generally used as a catalyst in anesterification reaction conducted using, as raw materials, an alcoholcompound and a carboxylic acid compound.

Incidentally, when the acid catalyst is used also as a drying agentdescribed later, it is not necessary to add other drying agent to theacid catalyst and the acid catalyst may be allowed to have a function ofa drying agent.

The acid catalyst is preferably a strong acid having an aciddissociation constant pKa of 3 or less, in view of the level of thecatalytic activity. As preferred examples of the acid catalyst, therecan be mentioned inorganic acid compounds such as sulfuric acid,phosphoric acid and the like, and organic acid compounds such astoluenesulfonic acid, trifluoroacetic acid and the like.

The amount of the acid catalyst used is not critical but is preferably0.001 to 1 part by mass, particularly preferably 0.01 to 0.1 part bymass per part by mass of the 2-alkyl-2-adamantanol. By using the acidcatalyst in an amount of the above range, a higher reaction rate isobtained and a side reaction can be prevented.

Further, in the present invention, there can also be used preferably, asthe acid catalyst, a cationic ion exchange resin having sulfonic acidgroup as the ion exchange group. The cationic ion exchange resin is notcritical as long as it has sulfonic acid group as the ion exchangegroup.

In general, ion exchange resins take a gel type or a porous type [e.g. amacroreticular (MR) type (referred to also as a high porous type)]. Anion exchange resin of any type can be used. However, use of a MR type ispreferred in view of the resin stability during reaction and the highreactivity. Incidentally, as to the sulfonic acid group as ion exchangegroup, there are a sulfonic acid (—SO₃H) type and a sulfonic acid salt(an alkali metal salt such as —SO₃Na) type. In the present invention,use of a sulfonic acid (—SO₃H) type is necessary because the ionexchange resin is allowed to act as an acid catalyst. A sulfonic acidsalt (an alkali metal salt such as —SO₃Na) type per se does not functionas an acid catalyst. However, it can function as an acid catalyst byconverting it into a sulfonic acid (—SO₃H) type by a known pretreatmentof ion exchange group such as hydrochloric acid treatment, sulfuric acidtreatment or the like. Such cationic ion exchange resins are marketedand available commercially.

When a cation exchange resin is used as the acid catalyst, ordinarilyits amount used is preferably 0.001 to 100 parts by mass, particularlypreferably 0.01 to 50 parts by mass per part by mass of the2-alkyl-2-adamantanol in view of the rate of reaction and the easinessof stirring. Preferably, the amount used is specifically controlleddepending upon the kind of the cation exchange resin used, by confirmingthe proceeding of the reaction by, for example, gas chromatography.

In the production process of the present invention, when a2-alkyl-2-adamantanol is reacted with a carboxylic acid compound usingan acid catalyst, to obtain an ester, it is essential to conduct thereaction in the presence of a particular drying agent.

The drying agent used in the present invention is an acidic or neutralinorganic compound which is a solid in a dried state at normaltemperature or water-absorbing high-molecular compound. With a dryingagent which is a liquid when dried, or with a basic drying agent, theadvantage of the present invention is unobtainable.

The drying agent is not critical as long as it can absorb the waterpresent in the solution and per se is acidic or neutral.

Incidentally, in the present invention, the solid material refers to asolid or a gel. Further, the drying agent referred to in the presentinvention includes a dehydrating agent.

The inorganic compound which is a solid at ordinary temperature in adried state, can be exemplified by magnesium sulfate, calcium sulfate,phosphorus pentoxide, a molecular sieve and a silica gel.

The water-absorbing high-molecular compound which is a solid material atordinary temperature in a dried state, can be exemplified by a cationicion exchange resin and a polyacrylamide gel.

These drying agents may be used singly or in combination of two or morekinds.

The amount of the drying agent used is not critical as long as it issufficient to absorb the water generated in the reaction. Ordinarily, itis determined appropriately depending upon the amounts of2-alkyl-2-adamantanol and carboxylic acid compound used and the kind ofdrying agent used. It is preferred to be ordinarily 0.1 to 100 parts bymass, particularly 0.2 to 50 parts by mass per part by mass of the2-alkyl-2-adamantanol.

By conducting esterification in the presence of such a drying agent, theproduction of an olefin compound (a by-product) brought about by thedehydration of 2-alkyl-2-adamantanol is prevented effectively and anintended ester compound can be obtained at a high yield.

The reaction of the 2-alkyl-2-adamantanol with the carboxylic acidcompound in the presence of the acid catalyst and the drying agent isnot critical and can be conducted by mixing these materialsappropriately. From the standpoints of the operability and the easinessof control of reaction conditions such as reaction temperature and thelike, it is preferred to dissolve or suspend a 2-alkyl-2-adamantanol anda carboxylic acid compound in a solvent, add thereto an acid catalystand a drying agent, and stirring them.

The solvent used is not critical as long as it is stable to acids.Preferred solvents are, for example, hydrocarbons such as hexane,toluene and the like, and chlorinated hydrocarbons such as methylenechloride, chloroform and the like from the standpoint of, for example,the solubility of compounds. The amount of the solvent used is notcritical. In view of the solubilities of starting material compounds andproduct compound, the reactor yield, etc., the amount is preferably 5liters or less, particularly preferably 2 to 1 liter per mole of thealkyladamantanol.

The reaction conditions are determined appropriately depending upon thekinds, amounts and concentrations of the individual starting materialsused. The reaction temperature is preferably 0 to 40° C., and thereaction time is preferably 1 to 48 hours. By selecting these reactionconditions, it is possible to conduct a reaction at a high reaction ratewith a side reaction being prevented. The proceeding of the reaction canbe confirmed by, for example, gas chromatography.

By thus conducting an esterification reaction, there can be obtained a2-alkyl-2-adamantyl ester having a structure obtained by dehydration andcondensation between a 2-alkyl-2-adamantanol and a carboxylic acidcompound.

For example, by conducting a reaction using, as the2-alkyl-2-adamantanol, 2-methyl-2-adamantanol and, as the carboxylicacid compound, acrylic acid or methacrylic acid, there is obtained2-methyl-2-adamantyl acrylate or 2-methyl-2-adamantyl methacrylate.

To recover an intended compound of 2-alkyl-2-adamantyl ester from thereaction mixture after esterification, the following method can beshown, for example. First, the drying agent is removed from the reactionmixture by filtration or the like; then, the drying agent-removedreaction mixture is washed with an aqueous alkali solution to neutralizethe acid catalyst in the reaction mixture. Further, water washing andextraction are conducted as necessary; the resulting mixture issubjected to vacuum evaporation to remove the solvent contained therein.Thereby, an intended ester compound can be isolated.

When the reaction is conducted using a cationic ion exchange resin as anacid catalyst, the acid catalyst and the drying agent can be removed byremoving the cationic ion exchange resin and drying agent used, byfiltration or the like. Therefore, by subjecting the resulting mixtureto vacuum evaporation to remove the solvent contained therein, withoutconducting water washing and extraction, an intended ester compound canbe isolated.

When the reaction is conducted using a cationic ion exchange resin as anacid catalyst and drying agent, the acid catalyst and drying agent canbe removed by removing, from the reaction mixture, the cationic ionexchange resin used, by filtration or the like. Therefore, by subjectingthe reaction mixture to vacuum evaporation to remove the solventcontained therein, without conducting water washing and extraction, anintended ester compound can be isolated.

The cationic ion exchange resin and the drying agent both removed byfiltration or the like can be regenerated by a known regenerationtreatment such as heat treatment, vacuum drying or the like and can bereutilized.

In the production process of the present invention, a side reaction issuppressed sufficiently and a main reaction proceeds selectively at ahigh conversion. Therefore, an intended compound of high purity can beobtained by a simple isolation method such as mentioned above. As aresult, it can be used per se in various applications without conductingfurther purification, depending on the application. When an intendedcompound of higher purity is needed, the isolated 2-alkyl-2-adamantylester can be subjected to further purification by a known method such ascolumn chromatography, distillation, recrystallization or the like,depending upon the properties of the ester.

According to the present invention, a side reaction is suppressed and amain reaction proceeds selectively at a high conversion; therefore, a2-alkyl-2-adamantyl ester of high purity can be obtained by a simpleoperation. Further, since no unstable acid halide compound is used, thereaction operation is simple.

EXAMPLES

The present invention is specifically described below by way ofExamples. However, the present invention is in no way restricted bythese Examples.

Examples of the First Invention Example 1

44 ml of a tetrahydrofuran solution containing 0.06 mole of methylmagnesium bromide was added into a 200-ml four-necked flask providedwith a stirrer and a drying tube filled with calcium chloride. The airin the flask was replaced by nitrogen. Then, into the flask was dropwiseadded 7.5 g (0.05 mole) of 2-adamantanone dissolved in 30 ml oftetrahydrofuran, with the temperature of the mixture in the flask beingcontrolled so as not to exceed 40° C. After the completion of thedropwise addition, the mixture in the flask was stirred at 50° C. for 3hours.

The reaction mixture was analyzed by gas chromatography (GC). As aresult, magnesium bromide salt of 2-methyl-2-adamantanol was formed bynearly 100%.

The reaction mixture (a tetrahydrofuran solution of magnesium bromidesalt of 2-methyl-2-adamantanol) was cooled to room temperature. Theretowas added 1.62 g (0.016 mole) of triethylamine. Then, into the flask wasdropwise added 6.90 g (0.066 mole) of methacrylic chloride in a nitrogenatmosphere with the temperature of the mixture in the flask beingcontrolled at 25° C. Stirring was continued at 25° C. after thecompletion of the dropwise addition. The proceeding of a reaction wastraced by GC. As a result, the reaction was almost complete in 3 hours.The conversion based on magnesium bromide salt of2-methyl-2-adamantanol, determined by GC was 95.5%.

To the reaction mixture was added 1.25 ml of deionized water to stop thereaction. 0.02 g of phenothiazine as a polymerization inhibitor wasadded to the reaction mixture. Then, vacuum evaporation was conducted toremove the solvent to obtain a distillation residue. 75 g of heptane wasadded to the residue. The heptane layer was washed with an aqueoussolution containing 1 mole/liter of ammonium chloride. The heptane layerwas further washed with an aqueous solution containing 10% of sodiumhydroxide and deionized water in this order. Then, heptane was removedby vacuum evaporation to obtain 11.6 g of a crude product of2-methyl-2-adamantyl methacrylate (0.048 mole, yield: 99.1% in terms ofmagnesium bromide salt of 2-methyl-2-adamantanol). This crude product of2-methyl-2-adamantyl methacrylate was analyzed by GC. As a result, thepurity based on GC peak area (this purity is hereinafter referred toalso as GC purity) was 93.1%.

Incidentally, GC purity 93.1% is high as the purity of2-methyl-2-adamantyl methacrylate; and this crude product can be usedper se as a product without conducting further purification, dependingupon the application.

Examples 2 to 7

An operation was conducted in the same manner as in Example 1 exceptthat the temperature of methacrylic chloride addition and thetemperature of reaction were changed as shown in Table 1. The resultsobtained are shown in Table 1. In Table 1, the conversion refers to aconversion based on magnesium bromide salt of 2-methyl-2-adamantanol,determined by GC analysis. The yield is a yield of a crude product of2-methyl-2-asamantyl methacrylate. The purity is a purity based on thepeak area of GC (the same applies in the following Tables regarding thefirst invention).

TABLE 1 Addition temperature of Reaction Reac- Exam- methacrylictempera- tion Conver- Yield Purity ple chloride ° C. ture ° C. time hrsion % % % 2 0 50 1.5 96.6 99.4 89.3 3 −20 50 1.5 95.5 99.3 90.1 4 25 2515.0 98.1 99.1 95.3 5 25 50 3.0 97.4 99.2 91.7 6 40 50 3.0 96.0 99.289.3 7 50 50 3.0 92.2 99.5 85.8

Examples 8 to 9

An operation was conducted in the same manner as in Example 1 exceptthat a tertiary amine shown in Table 2 was used. The results obtainedare shown in Table 2.

TABLE 2 Conversion Yield Purity Example Tertiary amine compound % % % 8N-methylmorpholine 95.8 99.6 91.5 9 Diisopropylethylamine 94.5 98.9 98.1

Examples 10 to 11

An operation was conducted in the same manner as in Example 1 exceptthat a solvent shown in Table 3 was used. The results obtained are shownin Table 3.

TABLE 3 Conversion Yield Purity Example Solvent % % % 10 Toluene 94.699.0 91.6 11 Diethyl ether 97.5 99.6 94.3

Examples 12 to 14

An operation was conducted in the same manner as in Example 1 exceptthat a carboxylic acid halide compound shown in Table 4 was used. Theresults obtained are shown in Table 4.

TABLE 4 Carboxylic Exam- acid halide Conver- Yield Purity ple compoundProduct sion % % % 12 Acetyl 2-Methyl-2-adamantyl 98.3 98.9 97.3chloride acetate 13 Acetyl 2-Methyl-2-adamantyl 90.5 99.3 89.8 bromideacetate 14 Benzoyl 2-Methyl-2-adamantyl 84.6 96.3 82.3 bromide benzoate

Example 15

28.6 g (1.18 moles, 1.1 times moles of 2-adamantanone) of magnesium and950 ml of tetrahydrofuran were added into a 3-liter four-necked flaskprovided with a stirrer and a drying tube filed with calcium chloride,followed by stirring. The flask inside atmosphere was converted intonitrogen. Into the flask was dropwise added, at room temperature, 112 gof methyl bromide (1.18 moles, 1.1 times moles of 2-adamantanone) withthe temperature of the mixture in the flask being controlled at 30° C.or less. After the completion of the addition, stirring was conducted at25° C. for 3 hours to synthesize methyl magnesium bromide.

Next, into the flask was dropwise added a solution of 160 g (1.07 moles)of 2-adamantanone dissolved in 460 ml of tetrahydrofuran, with thetemperature of the mixture in the flask being controlled so as not toexceed 50° C. After the completion of the dropwise addition, the mixturewas stirred at 50° C. for 3 hours.

The proceeding of a reaction was confirmed by GC. As a result, magnesiumbromide salt of 2-methyl-2-admantanol was formed by nearly 100%.

The resulting tetrahydrofuran solution of magnesium bromide salt of2-methyl-2-admantanol was cooled to room temperature. Thereto was added27.1 g (0.27 mole) of triethylamine, and the mixture was heated to 40°C. Then, into the flask was dropwise added, in a nitrogen atmosphere,139.9 g (1.34 mole) of methacrylic chloride with the temperature of themixture in the flask being controlled so as not to exceed 45° C. Afterthe completion of the dropwise addition, stirring was conducted at 50°C. The proceeding of a reaction was traced by GC. As a result, thereaction was nearly complete in 3 hours.

The conversion based on magnesium bromide salt of2-methyl-2-adamantanol, determined by GC analysis was 97.4%.

25 ml of deionized water was added to the reaction mixture obtained, tostop the reaction. Then, 0.5 g of phenothiazine as a polymerizationinhibitor was added and vacuum evaporation was conducted for solventremoval. To the residue was added 750 g of heptane. The heptane layerwas washed with an aqueous solution containing 1 mole/liter of ammoniumchloride. The heptane layer was further washed with a 10% aqueous sodiumhydroxide solution and deionized water, and heptane was removed byvacuum evaporation to obtain 247.8 g of a crude product of2-methyl-2-adamantyl methacrylate (1.05 moles, yield: 94.9% based onmagnesium bromide salt of 2-methyl-2-adamantanol). The GC purity of thiscrude product of 2-methyl-2-adamantyl methacrylate was 90.7%.

Of the crude product of 2-methyl-2-adamantyl methacrylate, 50.2 g wassubjected to vacuum distillation at a vacuum of 0.3 mmHg to collect afraction having a GC purity of 98% or more. As a result, there could beobtained 2-methyl-2-adamantyl methacrylate of GC purity of 98.4% in anamount of 38.0 g (0.16 mole, yield: 74.9% in terms of magnesium bromidesalt of 2-methyl-2-adamantanol).

Comparative Example 1

44 ml of a tetrahydrofuran solution containing 0.06 mole of methylmagnesium bromide was added into a 200-ml four-necked flask providedwith a stirrer and a drying tube filled with calcium chloride. There towas dropwise added, at room temperature in a nitrogen atmosphere, asolution of 7.5 g (0.05 mole) of 2-adamantanone dissolved in 30 ml oftetrahydrofuran, with the temperature of the mixture in the flask beingcontrolled so as not to exceed 40° C. After the completion of thedropwise addition, the mixture was stirred at 50° C. for 3 hours. Theproceeding of a reaction was confirmed by GC. As a result, magnesiumbromide salt of 2-methyl-2-adamantanol was formed by nearly 100%.

The resulting tetrahydrofuran solution of magnesium bromide salt of2-methyl-2-adamantanol was cooled to room temperature. Thereto wasdropwise added, in a nitrogen atmosphere, 6.27 g (0.06 mole) ofmethacrylic chloride with the temperature of the mixture in the flaskbeing controlled at 25° C. After the completion of the dropwiseaddition, stirring was continued at 25° C. and the proceeding of areaction was traced by GC. As a result, the conversion based onmagnesium bromide salt of 2-methyl-2-adamantanol was 69.4% in 3 hoursand 86.3% in 15 hours.

1.25 ml of deionized water was added to the reaction mixture to stop thereaction. Further, 0.02 g of phenothiazine as a polymerization inhibitorwas added to the reaction mixture. Vacuum evaporation was conducted toremove the solvent to obtain a residue. 75 g of heptane was added to theresidue. The heptane layer was washed with an aqueous solutioncontaining 1 mole/liter of ammonium chloride. The heptane layer wasfurther washed with an aqueous solution containing 10% by mass of sodiumhydroxide and deionized water. Then, heptane was removed by vacuumevaporation to obtain 12.2 g of a crude product of 2-methyl-2-adamantylmethacrylate (0.052 mole, yield: 104.3% in terms of magnesium bromidesalt of 2-methyl-2-adamantanol). This crude product of2-methyl-2-adamantyl methacrylate had a GC purity of 77.1%.

Comparative Example 1 is an case in which a reaction was conducted usingno tertiary amine compound in Examples 1 and 4. As shown in the resultsof Examples 1 and 4, the conversions after 3 hours and 15 hours when areaction was conducted in the co-existence of a tertiary amine compound,is 95.5% and 98.1%, respectively. In contrast, in Comparative Example 1,the conversion after 15 hours is as low as 86.3%. In Comparative Example1, the purity of the crude product obtained in the same manner is low aswell.

Thus, it is clear that when comparison is made in the same reactionsystem, a reaction in the co-existence of a tertiary amine compoundgives an improved conversion and an improved purity of crude product.

Examples of the Second Invention Example 16

830 mg (5 m mole) of 2-methyl-2-adamantanol and 4.32 g (50 m mole) ofmethacrylic acid were dissolved in 5 ml of methylene chloride. Theretowere added 100 mg of concentrated sulfuric acid (96% by mass) and 1.0 gof magnesium sulfate. Stirring was conducted at room temperature (about25° C.) for 16 hours. Then, the reaction mixture was poured into 50 mlof an aqueous solution containing 10% by mass of sodium hydroxide,followed by extraction with 50 ml of ether. The resulting ether layerwas subjected to evaporation to remove the solvent contained therein, toobtain 1.2 g of a crude product. The crude product was analyzed by gaschromatography. The content (purity) of 2-methyl-2-adamantylmethacrylate in the crude product was 84% based on the peak area of GC.Incidentally, this purity of 84% is high as the purity of2-methyl-2-adamantyl methacrylate. A product of this purity can be usedper se, depending upon the application, without conducting furtherpurification. The above crude product was analyzed by liquidchromatography and gel permeation chromatography; as a result, there wassubstantially no impurity peak not appearing in the above gaschromatography. Therefore, the yield of 2-methyl-2-adamantylmethacrylate determined by the liquid chromatography and the gelpermeation chromatography was 84% which was equal to the purity.

Example 17

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 16 but using no methylene chloride. The yield of2-methyl-2-adamantyl methacrylate was 84%.

Example 18

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 1 except that 2.16 g (25 m mole) of methacrylic acid wasused and the reaction was conducted at 4° C. for 6 hours. The yield of2-methyl-2-adamantyl methacrylate was 81%.

Examples 19 to 21

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 1 except that methylene chloride was replaced by a solventshown in Table 1. The results are shown in Table 5.

TABLE 5 Example Solvent Yield % 19 Heptane 75 20 Toluene 74 21 Ethylacetate 72

Example 22

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 17 except that in place of using concentrated sulfuricacid and magnesium sulfate, 200 mg of phosphorus pentoxide was used as acatalyst and dehydrating agent. The yield of 2-methyl-2-adamantylmethacrylate was 69%.

Examples 23 to 25

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 16 except that in place of using concentrated sulfuricacid, an acid catalyst shown in Table 6 was used in an amount shown inTable 6. The results are shown in Table 6.

TABLE 6 Example Acid catalyst/amount used Yield % 23 Phosphoric acid/100mg 74 24 p-Toluenesulfonic acid/200 mg 71 25 Trifluoromethanesulfonicacid/50 mg 74

Example 26

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 16 except that methacrylic acid was replaced by 3.1 g (25m mole) of benzoic acid and magnesium sulfate was replaced by 2 g ofMolecular Sieve 4A. The yield of 2-methyl-2-adamantyl benzoate was 71%.

Example 27

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 17 except that methacrylic acid was replaced by 3.0 g (50m mole) of acetic acid. The yield of 2-methyl-2-adamantyl acetate was74%.

Example 28

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 17 except that methacrylic acid was replaced by 3.6 g (50m mole) of acrylic acid. The yield of 2-methyl-2-adamantyl acrylate was85%.

Example 29

33.2 g (0.2 mole) of 2-methyl-2-adamantanol was dissolved in 172.2 g(2.0 mole) of methacrylic acid. Thereto were added 4.0 g of concentratedsulfuric acid (96% by mass) and 40.0 g of magnesium sulfate. Stirringwas conducted at room temperature (about 25° C.) for 4 hours. Then, thereaction mixture was dissolved in 141.0 g of heptane. The resultingsolution was washed with an aqueous solution containing 10% by mass ofsodium hydroxide and deionized water in this order.

The resulting organic layer was subjected to evaporation to remove thesolvent contained therein, to obtain 42.9 g of a crude product. Thecrude product was analyzed by gas chromatography. As a result, thecontent of 2-methyl-2-adamantyl methacrylate in the crude product was84%.

The crude product of 2-methyl-2-adamantyl methacrylate was subjected tovacuum distillation at a vacuum of 0.3 mmHg to obtain 31.7 g (yield:68%) of 2-methyl-2-adamantyl methacrylate. This product had a purity of97.5% when analyzed by gas chromatography.

Example 30

830 mg (5 m mole) of 2-methyl-2-adamantanol and 4.32 g (50 m mole) ofmethacrylic acid were dissolved in 5 ml of methylene chloride. To thesolution were added 1.0 g of Amberlist-15 (a product of OrganoCorporation, a macroreticular type, a sulfonic acid type) as a cationicion exchange resin and 3.0 g of anhydrous calcium sulfate. Stirring wasconducted at room temperature (about 25° C.) for 10 hours. Then, thereaction mixture was filtered to separate Amberlist-15 and anhydrouscalcium sulfate. The separated Amberlist-15 and anhydrous calciumsulfate were washed with 20 ml of methylene chloride. The washings werecombined with the filtrate obtained previously. The combined filtrateand washings were subjected to evaporation to remove the solvent, etc.contained therein, to obtain 1.2 g of a crude product. The crude productwas analyzed by gas chromatography. As a result, the content of2-methyl-2-adamantyl methacrylate in the crude product was 84%. Theabove crude product was analyzed by liquid chromatography and gelpermeation chromatography; as a result, there was substantially noimpurity peak which is not appearing in the above gas chromatography.Therefore, the yield of 2-methyl-2-adamantyl methacrylate determined byliquid chromatography and gel permeation chromatography was 84% whichwas equal to the purity.

Example 31

The Amberlist-15 and anhydrous calcium sulfate separated by filtrationin Example 30 were regenerated by heating at 100° C. for 4 hours at avacuum of 0.2 mmHg. In the same operation as in Example 30 except that1.0 g of the regenerated Amberslist-15 and 3.0 g of the regeneratedanhydrous calcium sulfate were used, and a reaction, a post-treatment,etc. were conducted. The yield of 2-methyl-2-adamantyl acrylate was 84%.

From this result, it is clear that a cationic ion exchange resin and adehydrating agent both used in a reaction can be reutilized by anappropriate regeneration treatment.

Example 32

An operation was conducted in the same manner as in Example 30 exceptthat no methylene chloride was used. As a result, the yield of2-methyl-2-adamantyl methacrylate was 84%.

Example 33

A reaction, a post-treatment and an analysis were conducted in the samemanner as in Example 15 except that no anhydrous calcium sulfate wasused and 3.0 g of Amberslist-15 was used as an acid catalyst anddehydrating agent. As a result, the yield of 2-methyl-2-adamantylacrylate was 74%.

Examples 34 to 35

A reaction, a post-treatment and an analysis were conducted in the samemanner as in Example 30 except that in place of anhydrous calciumsulfate, a dehydrating agent shown in Table 7 was used in an amountshown in Table 7. The results are shown in Table 7.

TABLE 7 Example Dehydrating agent/g Yield % 34 Molecular Sieve 4A/1.0 7335 Magnesium sulfate/1.0 66

Example 36

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 30 except that methacrylic acid was replaced by 3.0 g (50m mole) of acetic acid. The yield of 2-methyl-2-adamantyl acetate was72%.

Example 37

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 30 except that methacrylic acid was replaced by 3.6 g (50m mole) of acrylic acid. The yield of 2-methyl-2-adamantyl acrylate was84%.

Example 38

33 g (0.2 mole) of 2-methyl-2-adamantanol and 172.2 g (2.0 mole) ofmethacrylic acid were dissolved in 200 ml of methylene chloride. To thesolution were added 40.0 g of Amberlist-15 and 120.0 g of anhydrouscalcium sulfate. Stirring was conducted at room temperature (about 25°C.) for 4 hours. Then, the reaction mixture was filtered to separateAmberlist-15 and anhydrous calcium sulfate. The separated Amberlist-15and anhydrous calcium sulfate were washed with 200 ml of methylenechloride. The washings were combined with the filtrate obtainedpreviously. The combined filtrate and washings were subjected toevaporation to remove methylene chloride and methacrylic acid to obtain86.2 g of a crude product. The crude product was analyzed by gaschromatography. As a result, the content of 2-methyl-2-adamantylmethacrylate in the crude product was 84%.

Of the obtained crude product of 2-methyl-2-adamantyl methacrylate, 50.0g was subjected to vacuum distillation at a vacuum of 0.3 mmHg to obtain26.7 g (yield: 57%) of 2-methyl-2-adamantyl methacrylate. The purity ofthis product determined by gas chromatography was 97.5%.

Comparative Examples 2 to 5

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 17 except that no magnesium sulfate was used andconcentrated sulfuric acid (96% by mass) was used as a catalyst anddehydrating agent. The composition of each crude product obtained andthe yield of 2-methyl-2-adamantyl methacrylate (intended product) areshown in Table 8.

TABLE 8 Compar- Concentrated ative sulfuric Methacrylate AdamantanolExample acid mg yield % % By-products % 2 100 47 45 2-Methylene-adamantane: 7 Others: 1 3 500 46 42 2-Methylene- adamantane: 7 Others: 14 1000 2 6 Complicated mixture: 92 5 5000 0 0 Complicated mixture: 100

Comparative Example 6

A reaction, a post-treatment, etc. were conducted in the same operationas in Example 16 except that no magnesium sulfate was used, hexane wasused as a solvent, and the reaction was conducted at a refluxingtemperature for 3 hours. 1.0 g of a crude product was obtained. However,the yield of 2-methyl-2-adamantyl methacrylate was 31%, the raw materialadamantanol remained by 22%, and 2-methyleneadamantane was formed by46%.

Comparative Example 7

A reaction was conducted at a refluxing temperature for 3 hours using nomagnesium sulfate but using a Dean-Stark dehydrating apparatus. Toluenewas used as a solvent. The other operating conditions were the same asin Example 16, and a reaction, a post-treatment, etc. were conducted.1.0 g of a crude product was obtained. However, the purity of2-methyl-2-adamantyl methacrylate in the crude product was 15% and2-methyleneadamantane was formed by 80%.

1. A process for producing a 2-alkyl-2-adamantyl ester, which comprisesreacting a magnesium halide salt of a 2-alkyl-2-adamantanol, representedby the following general formula (1):

(wherein R¹ is an alkyl group of 1 to 6 carbon atoms, and X is a halogenatom) with a carboxylic acid halide compound in the presence of atertiary amine compound of 0.01 to 0.5 mole per 1 mole of the carboxylicacid halide.
 2. A process for producing a 2-alkyl-2-adamantyl esteraccording to claim 1, wherein in the general formula (1), R¹ is an alkylgroup of 1 to 3 carbon atoms.
 3. A process for producing a2-alkyl-2-adamantyl ester according to claim 1, wherein the carboxylicacid halide is acrylic chloride or methacrylic chloride.
 4. A processfor producing a 2-alkyl-2-adamantyl ester according to claim 1, whereinthe carboxylic acid halide is used in an amount of 0.8 to 2.0 moles per1 mole of the magnesium halide salt of a 2-alkyl-2-adamantyl ester.
 5. Aprocess for producing a 2-alkyl-2-adamantyl ester according to claim 1,wherein the tertiary amine compound is triethylamine orN-methylmorpholine.
 6. A process for producing a 2-alkyl-2-adamantylester according to any of claim 1, wherein the reaction is allowed toproceed in a solvent.
 7. A process for producing a 2-alkyl-2-adamantylester according to claim 2, wherein the carboxylic acid halide is usedin an amount of 0.8 to 2.0 moles per 1 mole of the magnesium halide saltof a 2-alkyl-2-adamantyl ester.